High level individuality in vocalizations of a well-known avian brood parasite: Asian koel (Eudynamys scolopacea L.)

The Asian koel (Eudynamys scolopacea) is a well-known brood parasitic bird that visits Pakistan every summer from India. This species produces at least five loud call types that are presumed to be used in territorial and mating behaviour. We noticed vocal differences among individuals in the wild and hypothesised that Asian koels produce individually distinct vocalizations. To test this, we recorded type 1 cooee calls, coe calls, type 1 coegh calls, type 2 coegh call and wurroo calls from 46 adult birds in the wild, and measured 15 different acoustic parameters, both spectral and temporal, for each vocalization type. We also measured the Potential of Individual Coding (PIC). Parameters having PIC values ≥1.1 were further analysed through stepwise cross-validated discriminant function analysis (DFA). The DFA accurately categorised 86.5% of the type 1 cooee calls, 95.7% of coe calls, 91.5% of the type 1 coegh calls, 82.2% of type 2 coegh calls and 83.3% of wurroo calls to the individuals from which these calls were recorded. Thus, consistent with our hypothesis, our results indicate that Asian koels produce individually distinct calls.